Location: Children's Nutrition Research CenterTitle: Comparison of leucine and dispensable amino acid kinetics between Indian women with low or normal body mass indexes during pregnancy) Author
Submitted to: American Journal of Clinical Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/25/2010
Publication Date: 8/1/2010
Citation: Kurpad, A.V., Dwarkanath, P., Thomas, T., Mhaskar, A., Thomas, A., Mhaskar, R., Jahoor, F. 2010. Comparison of leucine and dispensable amino acid kinetics between Indian women with low or normal body mass indexes during pregnancy. American Journal of Clinical Nutrition. 92(2):320-329. Interpretive Summary: It is believed, that pregnant women with normal body weight, break down more of their body proteins to provide extra amounts of special compounds, called amino acids to their growing womb and to the baby growing in their womb. Pregnant women also provide more of these amino acids by using the protein they get from their meals more efficiently. It is not known, however, if underweight women can make these adjustments during pregnancy to provide the same amount of amino acids to their babies. In this study performed in pregnant women with normal and low body weights, we found that the underweight women used their dietary proteins less efficiently. However, they were still able to provide sufficient amino acids because they increased the amount of protein they were eating by 50%. This is important because it suggests that underweight women need to eat extra protein during their pregnancy in order to deliver a normal weight baby.
Technical Abstract: Evidence suggests that in women with a normal to high body mass index (BMI; in kg/m(2)), the extra amino acids needed during pregnancy are met through reduced oxidation. It is not known whether a woman with a low BMI can make this adaptation successfully. The objective was to measure and compare leucine kinetic parameters and alanine-nitrogen, glutamine amide-nitrogen, and glycine and cysteine fluxes in Indian women with a low and normal BMI in early and midpregnancy. Fasted- and fed-state kinetics were measured by infusing 1-[(13)C]leucine, [(2)H(2)]cysteine, [(2)H(2)]glycine, [5-(15)N]glutamine, and [(15)N]alanine in groups of 10 women with a low BMI (<18.5) and 10 women with a normal BMI (18.5-25) in the first and second trimesters of pregnancy. Leucine, glutamine, glycine, and cysteine fluxes were faster in women with a low BMI in both trimesters, but there was no difference in alanine flux between groups. This difference was explained in the first trimester by a higher proportion of fat-free mass in low-BMI women. Leucine oxidation and percentage of dietary leucine oxidized were higher in low-BMI women in both trimesters, but nonoxidative disposal was not different between groups. Although they use dietary protein less efficiently, low-BMI women maintain net protein synthesis at the same rate as do normal-BMI women and produce similar quantities of labile nitrogen for the de novo synthesis of other dispensable amino acids such as glycine and cysteine. The extra amino acids required for increased maternal protein synthesis during pregnancy are provided by an overall decrease in amino acid catabolism in women with normal or low BMI.